I am still think of what the doctrine of each factions (NCR, Legion, BoS, House/Yesman Courier).
NCR would undoubtly closer to American in both Coh1 and Coh2 games, but minus the artillery.
Whole base upgrades are to increase the supply lines capability, which mean in game is boosting your income. And increased pop size and unlocking Enclave and prewar equipment as the ultimate reward
Legion is obvious closer to Soviet both in Eastern Front mod of CoH1 and Vanilla Soviet in CoH2. They have low upkeep and utilized subversive tactics. The Soviet are too rich in both games in term of strategy being used beyond the standard Zerg Rush tactic, including but not limited to urban combat specialization, breakthrough with heavy units, and booby traps.